1. Field of the Invention
The present invention relates to hydrolyzed nitrilotriacetonitrile compositions, nitrilotriacetonitrile hydrolysis methods for preparing the hydrolyzed nitrilotriacetonitrile compositions, and methods for using same.
More particularly, the present invention relates to hydrolyzed nitrilotriacetonitrile compositions, where the method provides an efficient and reproducible nitrilotriacetonitrile hydrolysis method or process for preparing the hydrolyzed nitrilotriacetonitrile compositions, and methods for using same, where the hydrolyzed nitrilotriacetonitrile compositions are substantially cyanide free.
2. Description of the Related Art
Historically, hydrolyzed nitrilotriacetonitrile compositions were obtained by hydrolyzing products over a period of time generally in excess of 3 hour in the presence of an acid as disclosed in U.S. Pat. No. 3,987,077 to Bragdon et. al. followed by boiling the reaction mixture including triacetonitrile in an aqueous metal hydroxide solution. In U.S. Pat. No. 4,547,589 to Shen, Shen prepared nitrilotriacetonitrile compositions in the presence of formaldehyde to remove free cyanide.
Generally, hydrolyzed products are characterized with inconsistencies in hue and composition. Examples of different lot samples are depicted in FIG. 3C. Besides the inconsistencies in composition and color, insoluble crystals mire integrity of hydrolyzed products where solutions of such products are desirable. Consequently, product performance and shelf life are often sacrificed. Additionally, free cyanide ubiquitously associates with nitriloacetonitrile and its resultant hydrolysis products. Free cyanide is highly toxic to both human and the ecosystem. As such, there is need to eliminate it completely or to non-toxic levels and produce hydrolyzed products that meet environmental regulations.
Although several methods for preparing hydrolyzed nitrilotriacetonitrile compositions and the resulting hydrolyzed nitrilotriacetonitrile compositions have been disclosed, there is a need in the art for a more efficient and effective synthetic approach to preparing hydrolyzed nitrilotriacetonitrile compositions, where the compositions have a desired low level cyanide concentration.